Blind baking the crust in this pie recipe is essential to keep it from getting soggy when the custardy filling is added.
Pulse the flour, sugar, and salt in a food processor to combine. Add butter and pulse until mixture resembles coarse breadcrumbs.
Transfer to a large mixing bowl and add the buttermilk.
Mix with a fork, adding more buttermilk by the tablespoon if needed, just until the dough comes together. Knead very lightly in the bowl until no dry spots remain.
Pat into a disk and wrap in plastic. Refrigerate for at least 4 hours.
Filling and assembly:
Preheat oven to 160C.
Roll out the pie dough on a lightly floured surface to a 35-centimetre round.
Transfer to a 22-centimetre pie dish, allowing the dough to slump down into dish.
Trim dough, leaving about a 2½-centimetre overhang. Fold the overhang under and crimp edge. Prick bottom all over with a fork.
Freeze for 15 minutes.
Line the pie crust with baking paper or tin foil, leaving an overhang. Fill with pie weights or dried beans.
Place pie dish on baking sheet and bake until crust is dry around the edge: about 20–25 mins.
Remove the baking paper and weights. Bake until surface looks dry: about another 10-12 mins.
Meanwhile, mix together the egg yolks, eggs, buttermilk, sugar, lemon zest, lemon juice, salt and saffron in a blender until smooth.
With motor running, add 2 tablespoons of flour, followed by the melted butter.
Tap blender jar gently on the countertop to burst any air bubbles in the mixture.
Pour the mixture into the cooked pie crust.
Bake the pie, rotating halfway through, until filling is set around the edge and the centre has a slightly wobble, about 55-65 mins.
Transfer pie dish to a wire rack and leave to cool.
Serve the pie with whipped cream.
For the pie dough:
1¼ cups plain flour
1 tablespoon sugar
½ teaspoon salt
115 grams chilled unsalted butter, cubed
¼ cup buttermilk
Filling and assembly:
2 tablespoons plain flour, plus extra
6 large egg yolks
3 large eggs
1¼ cups buttermilk
1¼ cups caster sugar
1 tablespoon lemon zest, finely grated
⅓ cup fresh lemon juice
¼ teaspoon salt
1 pinch saffron threads
2 tablespoons unsalted butter, melted and slightly cooled
Whipped cream (for serving)